1 person found this helpful
To begin where you end, you may copy in front, reduce the size of the copy, select both, and Object>Compound Path>Make.
Do you wish a piece of a pie or an arc?
If the former, you may create two (orthogonal or with another angle if wished) lines through the centre (you may rotate a copy), select all, Pathfinder>Divide, and delete the rest.
If the latter, for 90 degrees just cut two adjacent Anchor Points (after rotating if needed) and delete the rest; for other angles, you may use two lines as described above, placed under the circle, use the Scissors Tool on the intersections, and delete the rest (Smart Guides are your friend).
Thanks for your response Jacob.
I was going to do a compound path as a quick fix, however I know - because I've done it by accident - that I can alter a circle so that it's got a hole in the middle, and then alter it so that it 'opens' to varying degrees - like stills of Pacman, for want of a much better description! The methods you suggested would of course do the job, but I was hoping to find out the way I'd done it before because it seemed like the proper way to do it. Must start making notes...!
I think I know what you might have done in the past.
If you make a polar grid using two radial dividers and one concentric divider and use the option to make compound path you can the easily manually rotate the two radial dividers. then join the ends of the two radial dividers and use the Object>Path>Divide Objects Below to cut
the donut like objet the polar grid created with the one concentric divider.
this what the polar grid did
With smart guides on you can easily match the angles are the same if you desire that a vertical smart guide will appear when they are aligned
Join the two lines and divide below and the remove.
You might have use a radar graph but I have have not figured that out as of yet.
This what you get of course when you delete the section divided.
You can change the angle of the radial dividers with the skew option but seems to only work on one radial at a time?